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Records of the Australian Museum (2017) Vol. 69 
1) are that the pallial oviduct is open in benthic Epitoniidae 
but closed in Janthina and Recluzia , Janthina and Recluzia 
lack an operculum in the adult although it is present in the 
larva and in all benthic Epitoniidae, and statocysts are present 
in benthic Epitoniidae but absent in Janthina - although 
Churchill et al. (2011a) demonstrated that statocysts are 
present in Recluzia. Also, Janthina species have a whitish 
to pale blue body with subdivided (forked) and, in some 
specimens, black or at least black-speckled cephalic 
tentacles, shown well by Cheng (1975: fig. 11), Okutani 
(1956: text-figs 4-6, 8) and Wilson & Wilson (1956: pi. 1, 
fig. 2; Fig. IB; Figs 4B-C, 5A, E) whereas the entire animal 
is yellow and the cephalic tentacles are single (undivided) in 
Recluzia species (Bennett, 1966: pi. 11, fig. 1; Churchill et 
al ., 2011a: fig. IB; Figs 6-7) and are undivided in benthic 
Epitoniidae. Exterior features of the animal of Janthina 
and Recluzia species are shown in Figs 4-7. The relatively 
well-known exterior anatomical characters of J. janthina are 
confirmed to be essentially identical in photographs of living 
animals of J. globosa , J. pallida and J. umbilicata illustrated 
here (Figs 5B-C, E). Some specimens of J. janthina have 
black or black-speckled cephalic tentacles and snout, as 
does the specimen of J. pallida illustrated here (Fig. 5B) 
but the photographs of J. globosa and some of those of J. 
janthina and other species published here (Figs 4B-C, E, 
5A, E) show that they have subdivided tentacles, but they are 
translucent blue and at most a little darker than the rest of the 
animal tissue, although perhaps only when contracted; black 
speckling is far from uniform. The head and snout also are a 
little larger and more protruding in Janthina species than in 
Recluzia species, so Janthina species have evolved a sinus 
in the outer lip to accommodate the permanently protruding 
head and snout (or, more accurately, adapted an earlier, 
smaller sinus at the base of the lip), whereas a sinus is not 
required by Recluzia. Recluzia species and four of the five 
living species of Janthina also lay stalked egg capsules on 
the underside of their floats, rather than the more numerous, 
small, sand-agglutinated, linked egg capsules of benthic 
Epitoniidae. The egg capsules are simple, smooth, slightly 
club-shaped cylinders with hemispherical distal ends in both 
Recluzia species (Figs 6-7), but are ovate-triangular with 
the distal end wider than the proximal one and with small 
spines around the distal end in Janthina species (Laursen, 
1953: figs 23, 27, 31, 37; Okutani, 1956: text-fig. 2). A 
further obvious difference is in the number of teleoconch 
whorls. This can range from as few as five to as many as 20 
in benthic Epitoniidae (Weil et al ., 1999: 118; 20 whorls in 
Claviscala LC kuroharai Azuma, 1960”, i.e., C. terebralioides 
Kilburn, 1975; Tsuchida, 2000: 329) whereas Recluzia 
lutea has 4.5-5.5 teleoconch whorls, R.johnii has 6-7, and 
Janthina species have only 3.5-5 teleoconch whorls. These 
distinctions from benthic Epitoniidae can all be understood 
as adaptations by Janthina and Recluzia to neustonic life 
suspended beneath a bubble float. Other characters important 
for classification are evaluated more fully below, in a review 
of the extensive previously published information on the 
biology and relationships of Janthina and Recluzia , amplified 
by new photographs of living specimens (Figs 4-7). 
Review of biology of 
Janthina and Recluzia 
Float and formation of bubbles. The two genera of 
neustonic Epitoniidae recognized here, Janthina and 
Recluzia , have been able to adopt a neustonic life because 
they float by means of a raft or float constructed from air 
bubbles coated with mucus that hardens on contact with 
seawater. The float is held in place against the mesopodium 
merely by a sheet of the same mucus. The animal must 
retain the float permanently to remain afloat, so the head, 
propodium and mesopodium remain permanently outside 
the shell. Wilson & Wilson (1956: 300, fig. 1) noted that 
the living animal floats with almost all of the animal and its 
float beneath the water surface, only a small part of the float 
protruding above the water-air interface (Fig. 1), but quite a 
light puff of air directed at the float “will make the snail scud 
along before it”. Each float bubble is constructed by cupping 
air in the propodium and coating the bubble with mucus from 
the pedal mucus gland, which secretes mucus that hardens on 
contact with seawater. It is also the source of mucus attaching 
the float to the foot and egg capsules to the float (Laursen, 
1953: fig. 4; Fretter & Graham, 1962: 115). The animal is 
able to form bubbles only while at the sea surface, in contact 
with air, and specimens that lose their float sink to the bottom 
and die. The foot must, therefore, remain outside the shell 
permanently to retain the float. Robertson (2007a: 4) claimed 
that “postlarval Janthina shells have never been recovered 
from deep-sea bottom sediments”, but that is not correct. 
Simroth (1895: 7) listed specimens of Janthina dredged at 
considerable depths in the North Atlantic by the Plankton 
Expedition and Locard (1898) did the same for specimens 
dredged by the Travailleur and Talisman. Empty specimens 
have been dredged in small numbers offshore in deep water at 
numerous localities around northern New Zealand (material 
in NMNZ, listed under relevant species below). Also, nearly 
all the many fossils collected in New Zealand, southern 
Australia, Japanese and the Azores represent specimens that 
sank to the seabed on the continental shelf and were enclosed 
in sediment. The type material of Kaneconcha knorri Kaim, 
Tucholke & Waren, 2012 (= Janthina chavani ) also was 
dredged buried in sediment in 3293-2827 m of water on 
the mid-Atlantic ridge (Kaim et al. 2012). In a remarkably 
similar case, the holotype of Eunaticina abyssalis Simone, 
2014 (= J. typica ) was dredged enclosed in sediment in 
1500-1575 m in the South Atlantic off Itaunas, Espiritu 
Santo State, Brazil. Obvious exceptions are the abundant 
specimens of J. chavani in Roe Calcarenite and Bridgewater 
Limestone in southern Australia and the excellent material 
of J. typica collected recently at La Esfinge, Gran Canaria 
Figure 4 (facing page 129). Living animals in aquaria. (A) Janthina janthina (Linnaeus) (centre) and J. pallida Thomson (left, and part of 
another float at right) together, showing different bubble sizes in floats, and J. janthina feeding on pink eggs of J. pallida beneath float; 
collected at Arina Beach, Heraklion, Crete. (B) Janthina janthina, collected on beach in northern New South Wales, Australia, clearly 
showing forked cephalic tentacles; (C-E) Janthina janthina, all data as for Fig. 4A; C, showing forked cephalic tentacles, lack of eyes, and 
teeth and odontophore protruding from mouth at end of extended snout; D-E, showing extended head and snout, odontophore visible in 
mouth, and partially expanded right epipodium lying over shell (A, C-E, reproduced with permission of Dimitris Poursanidis, Heraklion, 
Crete; B, reproduced with permission of Denis Riek, Bmnswick Heads, New South Wales). Scale bars 10 mm. 
